Vacuum cleaner filter bags are arranged in the interior of the housing of a vacuum cleaner to collect the aspirated dust. To fasten the vacuum cleaner filter bag in the interior of the housing, vacuum cleaner filter bags comprise a corresponding holding plate via which the vacuum cleaner filter bag can be fixed on a holding device provided in the interior of the housing.
Such holding plates comprise a through opening through which an air stream with dust particles can enter into the interior of the filter bag. It is desired for various reasons that this through opening can be closed. On the one hand, when a filled vacuum cleaner filter bag is disposed off, a closed through-opening can prevent dust that has accumulated in the filter bag from exiting. Furthermore, some vacuum cleaner filter bags comprise loose particles, e.g. for odor absorption. To prevent such particles from falling out of the bag, it is also of advantage when the through opening is closed.
Such a holding plate with a through opening that can be closed by means of a closing element is known from WO 01/26526. In this holding plate a leaf spring cooperates with the closing element, and the spring characteristic is here chosen such that starting from a closing position the bending force first increases considerably and then drops almost suddenly to a minimum to rise again thereafter. The drawback of this holding plate is that the bending force rises relatively strongly in the case of large opening angles. A complete opening of the through opening, which during operation must be accomplished through the vacuum stream of the vacuum cleaner, is thereby rendered difficult.
A further holding plate is known from DE 102 09 718. In this holding plate a spring element for a closing flap is configured as a tension spring mounted on the side of the closing flap on which it is tension-loaded when the closing flap is opened. The drawback is here that during operation of the vacuum cleaner this spring element is always positioned in the flow path of the air flow, whereby dirt is collecting on the spring. Such dirt, which is often in the form of fibers, impairs the function of the spring and the closing function of the flap. Moreover, the tension spring is prone to high wear caused by impinging dirt particles.
A further holding plate with a closing flap and a tension spring is described in DE 44 15 350.